i have factory k planes and they work great but, when using the switch that controls them at the same time one works faster than the other up or down . shouls i care about this or is this normal , how do i change the fluid in them . there is a flat head screw that is turned half way out on both pump bodies what is that for ? any help is appreciated .

I'm not sure if this helps but mine do the exact same thing. I get them about where I want them then fine tune with the individual switches. My drives trim at different rates as well.

Bought new pumps once and they are still off a little in speed vs each other....same with my drives.

my port is 2 times faster. I just bought a used pump to get the pump body out and switch it.

You need to open the motor up and clean the surface the brushes ride on, they get corrosion there and slow down.

While your in there grease the bushing between the valve body motor. They get dry and turn hard after a while too.

thanks for info guys , i will try cleaning the motors and see what happens . does the bottom (large oil filter looking part ) un - screw and thats where the fluid is